One of my BA hens broke her leg in half (she got away from the fox, though!) and I set it between 2 sponges.
I used 2 stiff sponges. New ones are too soft. I used one that had been wet and allowed to dry so that it was stiff. I cut it in half legnthwise to the same size as her leg - her entire leg. I then put the leg as straight as I could, placed the stiff sponge pieces on either side & vet-wrapped them. I left it on for 3 weeks.
week #1 - she mostly sat around... hopped to food & water
week #2 - started to put a little weight on foot, but still wouldn't roost
week #3 - was walking with a limp, but almost normally
At the end of 3 weeks, I took off the splint. She has a large deformed bump (probably calcium deposits at this point) now, but she walks, jumps, and roosts normally. She favored it a bit at first, but I'm just glad she can still walk. She literally escaped from the jaws of a fox!